The present invention broadly relates to initial velocity measuring devices and, more specifically, pertains to a new and improved construction of a V.sub.0 -measurement device or muzzle velocity measuring device with which the muzzle or initial velocity of a projectile fired from a weapon is determined and which comprises two measurement coils arranged in mutual spaced relationship which transmit a signal upon passage of the projectile.
Generally speaking, the method of the present invention serves for calibrating a device for measuring the initial or muzzle velocity of a projectile fired from a weapon and comprises the steps of employing a V.sub.0 -measurement device or muzzle velocity measuring device for measuring an initial or muzzle velocity of a projectile and comprising a first measurement coil having a first magnetic field focus and a second measurement coil having a second magnetic field focus and arranged in mutual axially spaced relationship for transmitting signals upon passage of a projectile, the first magnetic field focus or center and the second magnetic field focus or center having a mutual axial separation distance.
In a known method of this type (cf. German Patent Publication No. 1,673,382, published Jan. 5, 1972) the electrical spacing of both coils is determined in advance by bringing a calibration body successively into those positions relative to each coil in which the output potential of a demodulator is equal to the threshold or trigger potential of a trigger and the distance measured between the two positions of the calibration body is employed for computing the initial or muzzle velocity.
This known calibration method has the disadvantage that, after calibration, the measurement coils of the V.sub.0 -measurement device may no longer be exchanged, or in other words, if the coils are exchanged the V.sub.0 -measurement device must be re-calibrated.